I am sure many just put the blades on without any balancing and it works fine. But I bet even with the low headspeeds that if everything is nicely balanced there maybe an improvement with a smoother machine and perhaps better headspeed and better acceration of the head in wind. I do know it is not good on a rc helicopter to not care about the cg and put tape at the end of the blade to balance. When run up they will still be out of balance.

Yes agree, the snag with this is there is so much play in the head, with the fit of the bearings in the holder and the bolt itself in the bearing. I shimmed the bolt with fine washers and used a 3mm nyloc nut which helped a bit.
Will see how it goes and if I dont like it I will have to do the normal CG blade balance as well.

When balancing helicopter blades you would always weigh and balance each blade to find the CG position of the blade, i.e. where it would balance if put flat on a knife edge.

If for example (extreme conditions) if all the weight was at the tip of one blade and all at the root of another, but their overall weight was the same, they still would balance ok doing a static balance as shown above with the brushless motor.
However because the dynamic balance is way out, the helicopter would still vibrate and shake.
So ideally what you want is to have all three blades weighing the same and each blade CG point in the same position.
So if you have one light blade it may be better to add the weight to the middle of the blade rather than at the tip.

The blades of the big wind turbines and some fullsize helicopters have moveable weight engineered into the blade, this can be screwed up and down the blade to adjust the balance.

There are loads of info about model helicopter blade balancing, do a search on google sometimes seeing it done makes it better to understand.

Yes to what Xairflyer said. You want the weight of the blades to be the same but just as important the weight distribution of the blades must also be the same before you actually balance them.. Say you want to balance two blades. One is twice as heavy as the other and most of the heavy blade's weight center is near the bolt hole. The lighter blade's weight center is much further out. You don't check the CG and you just put put it on a balancer. You add weight to the light blade at the tip and it balances out perfect but in reality the light blade is still way lighter than the heavy one.
I also put a spacer from my Trex 450 parts bin and finished off with a nylock nut to take out the slop of the rotor head bolt. too bad it is so cold as I have yet to maiden the bird.

While the snow continues to fall and the maiden flight is delayed till more favorable conditions I have plenty of time to waste playing with my Auto-G Decided that the AG is missing a pilot so drafted Kermit to take over those duties. He is pretty light so hopefully the CG won't be too far forward. Not sure about the additional side area but he is stuck on with Velcro so can be quickly grounded if that presents a problem! Anyway, he looks cute sitting in the "cockpit" battery hatch Best, Aero